Do you know if the two writers [ ] here tomorrow?I am not su

Do you know if the two writers [ will get ] here tomorrow?
I am not sure.If they [ arrive ],I'll ring you up.
第一句对将来要发生的事进行提问,明天那两个作家会来吗?will可以表示将来,get here意为“到这里,来这里”
第二句也是在谈将来发生的事情,不过是假设句：如果他们来了,我会给你打电话.主句是I'll ring you up,从句是由if引导的If they arrive.在表示将来的句子中,如果主句用了will表将来,则从句的时态均用一般现在时,即arrive